1. Field of the Invention
The present invention relates to the transmission, in particular in broadband networks, of data in packets, these packets comprising a header at a first carrier frequency, followed by an information field at a second carrier frequency, the start of transmission of the field being tied to the start of transmission of the header of the corresponding packet.
2. Discussion of the Background
It is known practice to transmit data in packets each comprising a header followed by an information field, the information afforded by the header making it possible, among other things, for the packet to be recognized and taken into account by the parties for whom it is intended.
It is known practice, utilizing a given frequency band for transmitting packets in a network, to define various transmission channels within the band and to allocate them to the transmitters of the network, either in a predetermined manner or on the basis of the transmission requirements; it turns out that such a method does not allow optimal use of the frequency band and is scarcely practical especially when a receiver is liable to receive packets on any of the channels and must therefore monitor the transmission of packets on all the channels.
It is also known practice to assign, within the band of transmission frequencies of a network, a channel to the headers; the receivers need now monitor only this channel and the information provided by the headers makes it possible to receive the fields, the latter being transmitted in the remainder of the useful band on a carrier frequency which may be constant or vary in a predetermined manner, for example in jumps, throughout the duration of the packet.